46 DEGENERATION I I 



motive appendages or limbs : they have dwindled and 

 degenerated to their present minute size and curiously 

 suggestive structure. 



Besides these there are other very numerous cases 

 of animal structure which can best be explained by 

 the hypothesis of degeneration. A discussion of these, 

 and a due exposition of the application of the hypo- 

 thesis of degeneration to the various groups just cited, 

 would involve a complete treatise on comparative 

 anatomy and embryology, and lead far beyond the 

 limitations of this little volume. 



All that has been, thus far, here said on the subject 

 of Degeneration is so much zoological specialism, 

 and may appear but a narrow restriction of the dis- 

 cussion to those who are not zoologists. Though we 

 may establish the hypothesis most satisfactorily by 

 the study of animal organisation and development, it 

 is abundantly clear that degenerative evolution is by 

 no means limited in its application to the field of 

 zoology. It clearly offers an explanation of many 

 vegetable phenomena, and is already admitted by 

 botanists as the explanation of the curious facts con- 

 nected with the reproductive process in the higher 

 plants. As a further example of its application in 

 this field, the yeast-plant may be adduced, which is 

 in all probability a degenerate floating form derived 

 from a species of mould. In other fields, wherever 

 in fact the great principle of evolution has been 

 recognised, degeneration plays an important part. 

 In tracing the development of languages, philo- 

 logists have long made use of the hypothesis of 



